Antenna base



FIG. 1 is a top, front, and right side environmental perspective view of a antenna base, showing our new design with the broken line structure being for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an antenna base, as shown and described. 